Integration of surgical instrument and display device for assisting in image-guided surgery

ABSTRACT

The invention relates to a surgical instrument comprising a handle portion or mounting portion and a functional portion and/or tip, wherein a display device is provided on the instrument and includes or enables displays which serve to assist in image-guided and/or navigation-assisted surgery. It also relates to a method for navigating a surgical instrument, wherein its position is determined and tracked by means of a medical tracking system and the position data is processed within the framework of medical navigation by means of a medical navigation system, wherein displays for navigation assistance and/or for assisting in image-guided surgery are provided on the instrument or on an element which is positionally assigned to the instrument or fastened to the instrument.

RELATED APPLICATION DATA

This application claims the priority of U.S. Provisional Application No.61/107,849, filed on Oct. 23, 2008, which is hereby incorporated in itsentirety by reference.

FIELD OF THE INVENTION

The invention relates to the integration of surgical instruments anddisplay devices (and, in specific embodiments, also a computationalunit) for assisting in image-guided surgery. In particular, it relatesto a surgical instrument comprising a handle portion or mounting portionand a functional portion, and to a method for navigating a surgicalinstrument. In specific embodiments of the present invention, thesurgical instrument is a pointing instrument—a so-called pointer.

BACKGROUND OF THE INVENTION

The functional portion mentioned is the portion with which theinstrument is equipped in accordance with its task, i.e. for example apointer tip in the case of a pointer instrument, a cutting edge in thecase of a scalpel, or a fastening portion (the fastening portion issuitable for enabling the instrument to be attached elsewhere, inparticular to other medical instruments, for example to a cutting block,an implant, a fraise, a saw, a drill, a chisel, a screwdriver, etc.) ora forcipate portion in the case of a pair of tweezers. It can also be orinclude a calibration receptacle which comprises a counter piece for anobject to be aligned, for example in order to quickly register an imagedata set using a scanned counter piece. In everyday parlance, thesefunctional portions are often also referred to as a “tip” of theinstrument, and the term “tip” is also used here in this sense. It canthus also describe functional portions of instruments which are notphysically embodied as a tip or embodied to be pointed.

Within the framework of navigation-assisted and/or image-guided surgery,the aforementioned pointers are in many cases used to register apatient, wherein a spatially tracked pointer is moved to various pointsand/or landmarks on the patient, in order to determine the spatialposition of these points and/or landmarks in the navigation coordinatesystem of a treatment room. These points or landmarks are then assignedto corresponding points or landmarks provided in an image data set (CT,MRI, etc.) acquired for example before the treatment, and stored in thenavigation system. On the basis of this, it is then possible to performthe navigation-assisted and/or image-guided treatment. In many cases,the instruments—i.e. including the pointer—are spatially tracked byoptical tracking systems, wherein markings (tracking markers) attachedto the instruments are tracked by cameras.

This sequence of registration steps is rather painstaking to completeusing tracked pointer instruments in accordance with the prior art andconventional navigation systems, because the person performing thetreatment has to constantly change their angle of view. In order to seewhich step follows as the next step in the registration procedure, it isnecessary to look at the navigation monitor, while in parallel withthis, the landmark on the patient is sought. In order to ensure that thelandmark has been acquired, the surgeon again has to look at the monitoror wait for a confirmation signal. If a number of points or a pointcloud (when acquiring surfaces) have to be scanned, the situationbecomes even more difficult because the correct position of the pointerhas to be verified again and again with the aid of the monitor—which isusually far away from the working environment.

SUMMARY OF THE INVENTION

It is an object of the present invention to facilitate the handling of asurgical instrument in the navigation environment, and in particular tomake the surgeon's interaction with the instrument in the navigationenvironment simpler. This also applies specifically to registrationtasks.

This object is solved in accordance with the invention by a surgicalinstrument comprising a handle portion or mounting portion and afunctional portion and/or tip, wherein a display device is provided onthe instrument and includes or enables displays which serve to assist inimage-guided and/or navigation-assisted surgery, and by a method fornavigating a surgical instrument, wherein its position is determined andtracked by means of a medical tracking system and the position data isprocessed within the framework of medical navigation by means of amedical navigation system, wherein displays for navigation assistanceand/or for assisting in image-guided surgery are provided on theinstrument or on an element which is positionally assigned to theinstrument or fastened to the instrument. The sub-claims definepreferred embodiments of the invention.

The surgical instrument in accordance with the present invention, whichcomprises a handle portion or mounting portion and a tip, has a displaydevice provided on it which includes or enables displays which serve toassist in image-guided and/or navigation-assisted surgery, i.e. in otherwords, the instrument itself displays information to the surgeon whichhe needs during the course of the treatment, such that the surgeon doesnot have to look away from the instrument and/or patient in order to beable to work with navigational assistance, wherein a registration methodis for example assisted in such a way that the work can proceed far moreintuitively during the landmark acquisition sequence. Pointers orpointing apparatuses which are embodied in accordance with the inventioncan not only positionally acquire landmarks or points but can alsoprovide information concerning the location of the landmark itself. Thesurgeon can concentrate his attention on the treatment location, i.e. onthe incision environment, and is not distracted by looking towards themonitor.

The display device can exhibit many different configurations within theframework of the present invention. On the one hand, it can include oneor more indicators which can be highlighted, in particular symbols orcharacters which can be illuminated or back-lit. On the other hand, itcan for example comprise an image display, in particular a screendisplay, which can be embodied in many different forms, whereinhigh-resolution color monitors or also energy-saving LCD image displaysare possible. In very general terms, it may be said that what isimportant within the framework of the invention is for the display toprovide information to the physician who would otherwise have to look atthe monitor. This can also include illuminated displays which are formedas points or strips and for example communicate load cases usingred-amber-green displays.

In one embodiment in accordance with the invention, the position of thesurgical instrument can be determined and tracked by means of a medicaltracking system, wherein the position data is processed within theframework of medical navigation by means of a medical navigation system.One particular embodiment of such a tracking system (in addition tooptical and magnetic tracking systems) is an integrated sensor system,specifically an inertial sensor system, which provides trackinginformation.

In one embodiment variant of the invention, a data processor isintegrated in the instrument and assigned to the display device, whereinthe activity of the instrument is tracked and identified by means of thedata processor, i.e. in other words, it is also perfectly possible toevaluate the navigation and tracking data in the instrument, whereinsaid navigation and tracking data can in turn be provided to the surgeonvia the display device.

The display device can be provided integrally with the instrument or canbe able to be integrated into the instrument and/or attached to theinstrument, specifically via an adaptor.

Instruments in accordance with the present invention can be providedwith tracking markings; these tracking markings can in particular alsobe attached in the region of the display device or attached to thedisplay device. This includes the scenario in which reflection markersor infrared LEDs are rigidly fastened to the instrument, for example twoor three tracking markers in a fixed geometric (characteristic)arrangement with respect to each other.

Providing such marker arrays and/or reference arrays is howeverelaborate and requires calibration steps. Tracking on the basis of theshape of an object alone is in turn not robust enough againstdistortions in the images, background or contrast, etc.

The present invention then ensures that this is remedied, using anembodiment of the surgical instrument in which the display itselfdisplays tracking markings or itself represents tracking markings or atracking marking. In other words, a surgical instrument or trackingreference (for example a bone tracker) is provided in accordance withthis embodiment of the invention, which can be automatically tracked orthe display contents of which are tracked. This removes the need toattach tracking markings, but the tracking will nonetheless still berobust enough in order to positionally track the instrument continuouslyand reliably using the display device, since the display can easily bemade bright enough to ensure that it is detected by the camera system.It can also be made clear enough by being colored, shaped or patterned.If, for example, the dimensions of the rectangular screen are known inthe navigation system, it is possible to determine the alignment andposition from the distortion in the angle of view in relation to a pointof interest on the instrument or in relation to the anatomicalstructure. It may also be possible to directly match the displayinformation, since it can be clearly described. The unit in which thetracking markings are displayed on the display device will also becapable of automatically or manually changing the tracking pattern, inorder to adapt to particular tracking situations or to assign differentinstruments to different specific tracking patterns which can then betracked in parallel.

In one embodiment in accordance with the invention, the display deviceincludes the navigation image display. This embodiment in accordancewith the invention enables the physician to perform the entirenavigation with image assistance, without once having to look away fromthe working environment in which the instrument is situated.

It is possible to also provide the data processor of the navigationsystem integrally with the instrument or to enable it to be integratedinto the instrument and/or attached to the instrument, specifically viaan adaptor. The physician would then have a portable navigation systemcomprising a display and a data processor on his instrument; providingthe other navigation components would be limited to providing the cameratracking system or an equivalent tracking system (magnetic tracking,etc.) and/or would even be completely omitted, i.e. if the navigationsystem is an inertial system which operates using acceleration, inertiaand/or angle sensors integrated in the instrument, i.e. in such cases,the integrated data processor can assume the function of evaluating aninertial sensor system in the instrument, in particular also inconnection with external and additional or redundant trackinginformation (for example, Kalman filtering), in order to improve 3Dlocalization.

One embodiment of an instrument in accordance with the invention ischaracterized in that the data processor and the display device areprovided as an integrated, specifically portable navigation system. Thisintegrated system, in particular the integrated navigation system, canbe able to be removably attached to the handle portion or mountingportion of the instrument via an adaptor. If the display device isdirectly tracked, the tracker is for example on the display and theadaptor has no tracker; if it is tracked for example via marker spheres,these are either on the display device or on the adaptor. Adapting ispreferably performed in a known spatial assignment of the instrument andthe adaptor with respect to each other and can be reproducibly releasedand reconnected.

The instrument can have a functional instrument tip as its tip (forexample, a pointer instrument); it is however also possible to provide afastening portion, for fixing the instrument, as the tip, such that theinstrument itself then becomes a tracker (a tracking marking/reference)which can for example be fastened to a bone.

The method in accordance with the invention serves to navigate asurgical instrument, in particular an instrument such as has beendescribed above in various embodiments. The position of the instrumentis determined and tracked by means of a medical tracking system and theposition data is processed within the framework of medical navigation bymeans of a medical navigation system, wherein displays for navigationassistance and/or for assisting in image-guided surgery are provided onthe instrument or on an element which is positionally assigned to theinstrument or fastened to the instrument.

When landmarks or surfaces are acquired and registered using theinstrument, which serves as a position indicator and/or pointer, thedisplay device can predetermine and assist in the selection of thelandmarks and/or surfaces. This also applies in principle to thesequence of acquisition.

It is in principle possible to control the display device using the dataprocessor which determines movements or point acquisitions with the aidof the navigation system or using sensors on the instrument. It is alsopossible to determine movements or point acquisitions with the aid of adefined movement of the trackers with respect to each other.

The visual navigation assistance can be output via a display devicewhich is formed as a screen, and the display device can display changingtracking markings, as already described above. It is also possiblewithin the framework of invention for the visual navigation assistancevia the display device to simultaneously show the tracking markings.

The instrument in accordance with the invention can be configured suchthat the display device—or a navigation system which is integrated inthe instrument and can include the display device—is provided as aseparate element which can be attached to the instrument and comprises asterile covering, in particular a sterile drape or a shell which issterile and/or can be sterilized. It is also conceivable for the handleportion or mounting portion and/or the functional portion and inparticular also components of the instrument which are attached to themto be formed as sterile disposable items, in particular as sterilelypackaged disposable items, specifically made of a plastic material.

The embodiments of the method in accordance with the invention exhibitat least all the advantages which have already been described above withregard to the implementations of the invention as a device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained below in more detail on the basis of theenclosed drawings and by referring to various embodiments. It caninclude any of the features described here, individually and in anyexpedient combination, which can represent a method, a device or a use.

FIGS. 1 to 3 show pointer instruments embodied in accordance with theinvention, comprising different display devices.

FIGS. 4 and 5 show pointers in accordance with the invention, comprisinga navigation screen which also serves as a tracking reference.

FIG. 6 shows an embodiment of the invention as a bone tracker.

FIG. 7 shows an instrument in accordance with the invention, as aportable navigation system comprising a disposable mounting (sterilesolution).

FIG. 8 shows another embodiment of a sterilely packaged, portablenavigation system.

DETAILED DESCRIPTION

In FIGS. 1 to 7, the surgical instruments have been provided in verygeneral terms with the reference signs 10, 20, 30, 40, 50, 60 and 70,respectively. The handles of the instruments 10, 20 and 30 bear thereference signs 11, 21 and 31, while the mounting portions of theinstruments 40, 50, 60 and 70 have the reference signs 41, 51, 61 and71, respectively. The latter mounting portions 41, 51, 61 and 71 areprovided as adaptor mountings for display units and/or data processingunits, in particular portable navigation systems 45, 55, 65, 75; theycan, however, also be fixed mountings. Throughout the figures, thedisplays bear the reference signs 13, 23, 33, 43, 53, 63 and 73,respectively, and markers and/or tracking markings are indicated by 12,22, 32, 42, 52, 62 and 72, respectively. In FIGS. 1 and 3, the referencesigns 14 and 34 indicate buttons on the instrument which influence thedisplay or enable inputs on the instrument which can also be relayed toan external navigation system.

In FIG. 2, the reference sign 24 indicates a sprung mounting of theinstrument tip 29. The spring presents the possibility of automaticallyrecording a point which is made known to the tracking system by shiftingmarker spheres with respect to each other in a defined way or by a forcesensor system.

The instrument tips 19, 29, 39, 49 and 59 are embodied as pointer tipsin FIGS. 1 to 5, while FIG. 6 shows an instrument tip 69 which comprisesa fastening means at its distal end. The reference signs 12, 22 and 32in FIGS. 1 to 3 indicate spherical reference markers, the reference sign42 in FIG. 4 indicates the exterior outline of the image display 43, andthe reference sign 52 in FIG. 5 indicates reference markers which aregenerated on the image display 53. A tracking camera 2, comprising twoindividual cameras, and a bone 4 are also shown in each of FIGS. 4, 5and 6; a reference array 6 comprising reference markers for the bone(bone trackers) is also shown in FIGS. 4 and 5, and FIG. 6 also shows anadditional pointer instrument 8.

In the following, reference shall initially be made to FIGS. 1 to 3, ineach of which a display 13, 23, 33 is provided which communicatesinstructions to the physician as to where a point on the patient'sanatomy is to be acquired in a registration procedure. This could beachieved either by graphic representations or text (FIG. 1) or inconjunction with a display which shows whether the landmark still has tobe acquired or has already been acquired. The latter applies for exampleto the back-lit button displays in FIG. 2, in which for example a buttonwhich is back-lit in red indicates that a certain landmark still has tobe acquired and a button which is back-lit in green means that thelandmark has already been acquired. The display can also giveinstructions—as in FIG. 3—as to how many points have already beenacquired or the proportion of the total points which have already beenacquired so far (bar display). This tells the user where and how manypoints and/or point clouds still have to be traveled using the pointertip, in order for example to register a bone surface, i.e. in particularfor morphing or surface matching using an image data set.

The pointer instruments shown in FIGS. 1 to 3 use reflective trackingmarkers 12, 22, 32 which can be detected by a tracking system (forexample, an infrared camera system). It is possible to use othertracking technologies, for example tracking active LED markers,electromagnetic tracking or acoustic tracking.

The pointer instruments in accordance with the present invention can notonly comprise displays but can also be equipped with a data processingunit which is software-controlled and can detect the acquisition of apoint or point cloud autonomously and/or with the aid of the navigationsystem. Inertia-acceleration sensors could for example detect thecurrent algorithmic integration of a pivoting movement of the pointer inorder to acquire the point, and consequently switch the representationon the display forwards from one registration screen to the next. Thediscrete displays of the embodiment according to FIG. 2 could becontrolled in a similar way. In this case, further communication withthe navigation system is no longer necessary, but can optionally beprovided and realized by the buttons 14, 34. Another way of realizingthis would be to shorten the distance between the two marker spheres 22in the embodiment according to FIG. 2 if a point is indicated by the tip29, wherein the tip is sprung towards the handle (sprung-mounted 24).

FIGS. 4 to 6 each show how a navigation system is provided whichconsists of a data processing unit and display unit 45, 55, 65 and anexternally provided tracking camera 2. It is conceivable for an externaltracking system to be (partially) omitted if the data and display unitis equipped with an inertial sensor system, wherein the units 45, 55 and65 can be discrete, separate and completely integrated navigation unitsand/or display units. They are fastened to the instrument via adaptormountings 41, 51 and 61. In the case of FIGS. 4 and 5, the instrumenthas a pointer tip 49, 59; in the case of FIG. 6, the tip 69 mounts theinstrument on the bone 4. Navigation information or user instructionsare displayed by the navigation units 45, 55 and 65, and this could beachieved either by graphic representations or text information. In orderthat the instruments can be positionally tracked in space using theoptical tracking system 2, the outline 42 of the screen and/or display43 and its three-dimensional alignment are detected by the camera system2 in the embodiment according to FIG. 4.

Alternatively, the tracking markers 52 are shown directly on the display53 in the embodiment in accordance with FIG. 5, i.e. it is possible togenerate specific patterns which generate “virtual markers”. The displayitself can be a pattern, since the display is defined at least inpartial aspects by the programming of the graphic user interface. Theincrease in robustness by using known graphic representations can alsomean that normal cameras (instead of infrared cameras) can be used.These solutions in accordance with the invention allow the informationdisplay to be combined with the tracker units within the line of sightto the tracking system 2. It is no longer necessary to additionallyattach tracking markers.

While the two instruments 40, 50 in FIGS. 4 and 5 can serve as pointerinstruments for registering landmarks, wherein the patient's anatomy isalso separately tracked (the bone 4 comprising the tracking reference6), the tracking system itself can be fastened to the instrument and viathe instrument to the bone 4 in accordance with the embodiment accordingto FIG. 6. This enables the bone 4 to be tracked via the instrument 60itself, using the rectangle of the display (see FIG. 4) or viasuperimposed markers (see FIG. 5). The instrument 60 comprising thenavigation and display system 65 thus serves both as a trackingreference and as a display for the surgeon, and an additional pointerinstrument 8 can be simultaneously tracked.

In all cases, the surgeon performing the treatment can obtain all thenavigation information without constantly having to look away from theworking environment, to look at a separate navigation monitor.

FIGS. 7 and 8 illustrate “sterile solutions” in accordance with theinvention, i.e. embodiments in which an instrument in accordance withthe invention comprising a display or a portable navigation systemattached to the display can be sterilely used in a simple anduncomplicated way, with the aid of disposable components for handleportions or mounting portions and/or for functional portions (tip).

Using such embodiments in accordance with the invention, it is possibleto use a combination of a navigation system 75 (comprising a display73), 85 and a surgical instrument 70 in a sterile environment, whereinin the embodiment according to FIG. 7, the holding means 71 and/or thetip 79 are (individually or both) formed as disposable items (which canbe used once), which can themselves also bear navigation referencemarkers 72. This part of the instrument would simply be provided,already sterilely packaged, in the operation environment and can bedisposed of after it has been used once. It can consist substantially orcompletely of plastic. The mounting portion 71 forms a framework intowhich the portable navigation system 75 can be inserted; it alsoincludes reference markers 72, and all manner of instrument tips can beattached to it (a pointer tip 79 is shown in this case). It can howeveralso be an L-shaped device attached to the mounting portion 71 (forregistering the distal joint line and the posterior joint line) or acutting block.

In the embodiment according to FIG. 7, the portable navigation system 75comprising the display 73 has been wrapped in a sterile drape (coveringof film) before being inserted into the mounting 71; this drape isindicated by a broken line and has been given the reference sign 74. Inthis way, the navigation system 75 (comprising the display 73) is thuslikewise sterilely provided and can be directly used together with theother sterile elements of the instrument. The instrument as a whole isembodied such that the user can easily interact with the navigationsystem or the display (for example, a touch-sensitive screen 73), whileit is held in the hand and used as a surgical instrument.

As shown in FIG. 8, the holding means can also comprise a holding plate81 comprising navigation markers 82, on which a navigation system(comprising a display 85) is placed and which is covered with a sterile,rigid covering (for example, a cover made of a transparent plasticmaterial). The navigation system can then for example be operated viathinner points or areas of the covering 84 (also possible in the regionof the screen) which it is possible to press through.

All the parts of the instrument in accordance with FIG. 7 or FIG. 8,produced in this way, can as a whole be provided as disposable parts inaccordance with the invention, including the mounting portion, theinstrument tip and the reference markings, such that the instrument nolonger requires a sterilizing effort. This specifically applies when thesterile cover 83, 74 is also provided as a disposable item.

Computer program elements of the invention may be embodied in hardwareand/or software (including firmware, resident software, micro-code,etc.). The computer program elements of the invention may take the formof a computer program product which may be embodied by a computer-usableor computer-readable storage medium comprising computer-usable orcomputer-readable program instructions, “code” or a “computer program”embodied in said medium for use by or in connection with the instructionexecuting system. Within the context of this application, acomputer-usable or computer-readable medium may be any medium which cancontain, store, communicate, propagate or transport the program for useby or in connection with the instruction executing system, apparatus ordevice. The computer-usable or computer-readable medium may for examplebe, but is not limited to, an electronic, magnetic, optical,electromagnetic, infrared or semiconductor system, apparatus, device ormedium of propagation, such as for example the Internet. Thecomputer-usable or computer-readable medium could even for example bepaper or another suitable medium on which the program is printed, sincethe program could be electronically captured, for example by opticallyscanning the paper or other suitable medium, and then compiled,interpreted or otherwise processed in a suitable manner. The computerprogram product and any software and/or hardware described here form thevarious means for performing the functions of the invention in theexample embodiment(s).

Although the invention has been shown and described with respect to oneor more particular preferred embodiments, it is clear that equivalentamendments or modifications will occur to the person skilled in the artwhen reading and interpreting the text and enclosed drawing(s) of thisspecification. In particular with regard to the various functionsperformed by the elements (components, assemblies, devices,compositions, etc.) described above, the terms used to describe suchelements (including any reference to a “means”) are intended, unlessexpressly indicated otherwise, to correspond to any element whichperforms the specified function of the element described, i.e. which isfunctionally equivalent to it, even if it is not structurally equivalentto the disclosed structure which performs the function in the exampleembodiment(s) illustrated here. Moreover, while a particular feature ofthe invention may have been described above with respect to only one orsome of the embodiments illustrated, such a feature may also be combinedwith one or more other features of the other embodiments, in any waysuch as may be desirable or advantageous for any given application ofthe invention.

What is claimed is:
 1. A surgical instrument, comprising: a handleportion or a mounting portion; a functional portion; a display deviceconfigured to display information to assist in at least one ofimage-guided or navigation-assisted surgery, the display devicecomprising an image display; and a data processor assigned to thedisplay device, wherein the data processor is configured to track andidentify activity of the surgical instrument, and wherein the displaydevice and the data processor are arranged in a common housing that isdetachably connected to the surgical instrument via an adapter, whereindetachment of the housing from the surgical instrument detaches thedisplay device and the data processor from the surgical instrument,wherein the display comprises or displays tracking markings that aretrackable by a tracking system.
 2. The instrument according to claim 1,wherein the display device includes at least one highlightableindicator.
 3. The instrument according to claim 2, wherein the at leastone highlightable indicator is configured to illuminate or back-lightsymbols or characters.
 4. The instrument according to claim 1, whereinthe image display is a screen display.
 5. The instrument according toclaim 1, further comprising an integrated sensor system configured toprovide tracking information, said tracking information processed by amedical navigation system.
 6. The instrument according to claim 5,wherein the integrated sensor system is an inertial sensor system. 7.The instrument according to claim 1, wherein the integrated dataprocessor in the instrument is configured to evaluate an inertial sensorsystem in connection with external and additional or redundant trackinginformation in order to improve 3D localization.
 8. The instrumentaccording to claim 7, wherein the external, additional or redundanttracking information includes information obtained via Kalman filtering.9. The instrument according to claim 1, wherein the display deviceincludes a navigation image display.
 10. The instrument according toclaim 1, wherein the data processor and the display device form anintegrated navigation system.
 11. The instrument according to claim 10,wherein the integrated navigation system is a portable navigationsystem.
 12. The instrument according to claim 10, wherein the integratednavigation system is removably attached to the handle portion ormounting portion via an adaptor.
 13. The instrument according to claim1, wherein the functional portion comprises at least one of a functionalinstrument tip including a fastening device configured to fixedly attachthe instrument to an object, or a calibration receptacle configured toreceive an object to be aligned to the instrument.
 14. The instrumentaccording to claim 1, wherein at least one of the display device or thedata processor comprises a sterile covering.
 15. The instrumentaccording to claim 14, wherein the sterile covering is a sterile drapeor a shell which is sterile.
 16. The instrument according to claim 1,wherein at least one of the handle portion, the mounting portion or thefunctional portion is formed as sterile disposable items.
 17. Theinstrument according to claim 16, wherein the sterile disposable itemsare sterilely packaged disposable items.
 18. The instrument according toclaim 17, wherein the sterilely packaged disposable items are made of aplastic material.
 19. The instrument according to claim 16, whereincomponents of the instrument which are attached to the handle portion ormounting portion or the functional portion are formed as steriledisposable items.
 20. The instrument according to claim 19, wherein thesterile disposable items are sterilely packaged disposable items. 21.The instrument according to claim 20, wherein the sterilely packageddisposable items are made of a plastic material.
 22. A method fornavigating a surgical instrument, comprising: providing a display deviceand a data processor assigned to the display device, the display deviceand the data processor arranged in a common housing that is detachablyconnected to the surgical instrument, wherein detachment of the housingfrom the surgical instrument detaches the display device and the dataprocessor from the surgical instrument; displaying information on thedisplay device of the surgical instrument to assist in at least one ofimage-guided or navigation-assisted surgery; using the data processor totrack and identify activity of the surgical instrument, whereinassisting in at least one of image-guided or navigation-assisted surgeryincludes simultaneously displaying tracking markings via the displaydevice.
 23. The method according to claim 22, wherein the surgicalinstrument is an instrument according to claim
 1. 24. The methodaccording to claim 22, further comprising using the surgical instrumentto acquire and register landmarks or surfaces of an object, saidsurgical instrument serving as a position indicator, wherein the displaydevice predetermines or assists in the selection of the landmarks orsurfaces.
 25. The method according to claim 22, further comprisingcontrolling the display device using the data processor, said dataprocessor configured to determine movements or point acquisitions withthe aid of a navigation system or using sensors on the instrument. 26.The method according to claim 22, further comprising controlling thedisplay device using the data processor, said data processor configuredto determine movements or point acquisitions with the aid of a definedmovement of trackers with respect to each other.
 27. The methodaccording to claim 22, wherein assisting in at least one of image-guidedor navigation-assisted surgery includes outputting information via thedisplay device.
 28. The method according to claim 22, further comprisingdisplaying on the display device changing tracking markings.